The aim of the research plan is to study the genetics of ribosomes synthesis in B. subtilis. Our laboratory has previously shown that most of the DNA base sequences complementary to 5S, 16S and 23S ribosomal rRNA are found in the same region of the subtilis chromosome as several mutations conferring resistance to certain antibiotics which affect ribosomal function. We have subsequently shown that some of these mutations conferring resistance in B. subtilis also cause changes in specific r-proteins or are very closely linked to genes which code for r-proteins. On the basis of this genetic evidence and on various kinetic data dealing with the synthesis of ribosomal components, we postulate that the genetic determinants for rRNA and r-protein are coordinately controlled. To provide evidence for the concept of the ribosomal "operon": A. We are mapping the genetic determinants for rRNA and several r-proteins and are mapping markers which confer resistance to ribosomally active antibiotics. B. We are studying the kinetics of rRNA and protein synthesis with cells undergoing dramatic increases in ribosome content per cell (spore germination).